1. Field of the Invention
The present invention relates to image processing, and more particularly, to methods of embedding information in an input image, extracting information from an input image, and apparatus thereof.
2. Description of the Prior Art
For general printing technology, users have to encrypt printed documents to ensure confidentiality and prevent important documents from being copied or exploited. In conventional technology, pixels within an image are modified provided those modifications are not easily noticeable to the human eye. For example, the lowest bit values of pixels or a number of pixels in conjunction with a special pixel position arrangement are adjusted. Conventional technology, however, usually has a very small information capacity or requires a large amount of computation at the expense of readability of documents to achieve the aforementioned goals. How to ensure the confidentiality of documents easily and quickly is still a significant topic in this field.
Furthermore, for some conventional technologies, encrypted information is distributed around the whole image of the document. After the document is cut, the encryption can not function properly upon the cut document since the document is no longer intact.